Furnace-regulator system



Mar. 27, 1928. 1,449,888. S c, A. BODDIE.

FURNACE REGULATOR SYSTEM.

FILED DEC. 3, I919- WITNESSES: INVENTOR Patented Mar. 27, 1923.

; UNITED STATES PATENT OFFICE.

CLARENCE A. BODDIE, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING-HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN SYLVANIA.

FURNACE-REGULATOR SYSTEM.

Application filed December 3, 1919. Serial No. 342,174.

To all whom it may concern:

Be it known that I, CLARENCE A. Bonnm, a citizen of the United States,and a resident of Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Furnace-Regulating Systems, of which the following is a specification.

My invention relates to regulator systems and particularly to regulatorsystems for governing the operation of the movable electrodes inelectric furnaces.

One object of my invention is to provide a furnace-regulator system thatshall have a main magnet for govermn the operation of each movableelectrode 1n accordance with the current flowing through it and thatshall be provided with two differentially-wound coils which co-operatewith the main magnet and are selectively connected across the electrodearc to prevent hunting action.

At the present time, it is customary .to govern the movements, of themovable electrodes in accordance with the current flowing through them.However, such regulation is impractical in some respects unless somemeans is provided for preventing so called hunting action.

In practicing my invention, each movable electrode is operated inaccordance with the current flowing through it, and means, comprisingtwo difl'erential windings, are selectively energized to so change thesetting of the main magnet as to prevent hunting action. In thepreferred form of practicing my invention, each electrode'is raised andlowered by means of an electrode motor and the motor is selectivelyoperated in a clockwise and in a counterclockwise direction by means oftwo switches. A main magnet, having three windings, is provided forselectively operating the two switches in accordance with the currentflowing through the electrode. One of said magnet windings is soconnected to the electrode circuit as to be operated in accordance withthe current flowing through the electrode. Two 'of the magnet windingsare differentially wound and are selectively connected across theelectrode are by the two switches in order to change the setting of themagnet and prevent so-c-alled hunting action. Means are also pr videdfor completing a dynamic-braking circuit through the electrode-motorarmature upon the simultaneous release of the two switches.

The single figure of the accompanying drawing is a diagrammatic view ofthe regulator system embodying my invention.

Referring to the drawing, an electric furnace 1, comprising threemovable electrodes 2, 3 and 4 and a receptacle 5, containing a bath ofmaterial 6, is connected to a threephase supply circuit comprisingconductors 7, 8 and 9. Y

Each of the movable electrodes 2, 3 and 4 is raised and lowered by meansof a separate electrode motor, and a regulator is associated with eachelectrode motor in order to operate the motor in accordance with thecurrent flowing through the electrode connected to it. Inasmuch as theelectrode motors and 'the regulators associated with them are similar inconstruction and operation, it is deemed sufficient to describe theconstruction and operation of but one electrode motor and one regulator,namely, the

A motor 10, comprising an armature 11 'and a field-magnet winding 12, isprovided for raising and lowering the electrode 4.

The field-magnet winding 12 is directly connected across an auxiliarysupply circuit comprising conductors l3 and 14, and the armature isselectively connected across the supply conductors 13 and 14 by means oftwo switches 15 and 16 in order to govern the direction of the rotationof the motor 10 and, accordingly, the position of the electrode 4. Thearmature 11 is mechanically connected to the electrode 4 in any suitablemanner, as by means of a winding reel 17 and a flexible connector 18which passes over a pulley 19.

A main magnet 20, comprising three windings 21, 22' and 23, is providedfor operating a contact arm 24 in accordance with the current flowingthrough the elec-' trode4. A core armature 25, which is'connected to thecontact arm 24 by means of the spring 26 and is provided with a dash pot27, is acted upon by means of the coils 21 to 23, inclusive, foreffecting movement of the contact arm 24. The wlnding 21 is connected tothe three-phase supply conductor 9 by means of a current transformer 28in order to be energized in accordance with the current flowing throughthe electrode 4. The two windings 22 and 23 are differentially woundrelative to each other and are selectively connected across the areproduced by the electrode 4 in order to so change the setting of themain magnet 20 as to prevent hunting action. The contact arm 24 isfulcrumed at 29 and carries a main contact member 30 which is adapted toengage the contact members 31 and 32 according to the operative posltionof the main magnet 20. The plunger of a dash pot 33 is pivotallyconnected to the contact arm 24 in order to adjust the speed of itsoperation.

The switch 15 comprises a wind1ng 34, whichis connected. across thesupply conductors 13 and 14 upon engagement of the main contact members30 and 31, and a core armature-35 which is operated by the winding 34.The core armature 35 is directly connected to two switch members 36 and37 and two interlock switch members 38 and 39. The two switch members 36and 37, upon operation of the switch 15, serve to connect the armature11 across the supply conductors 13 and 14 to efiect rotation of themotor 10 in a counter-clockwise direction. The interlock switch member38 serves to connect the winding 23 across the arc produced by theelectrode 4. The winding 23 is wound to oppose the action of the winding21 and, consequently, upon operation of the switch 15, the interlockswitch member 38 effects a reduction in the strength of the main magnet20.

The switch 16 comprises a winding 40, which is connected'across, thesupply conductors 13 and 14 upon engagement between the main contactmembers 30 and 32, and a core armature 41 which is controlled by thewinding 40. The core armature 41 is directly connected to two switchmembers 42 plete an energizing circuit for a brake magnet 46 from thesupply conductors 13v and 14. The brake magnet 46 completes adynamic-braking circuit for the armature 11 through a resistor 47 Ifcurrent above normal value flows through the electrode 4, theenergization of T he interlock switch member- 44,

creased current flow through the winding 21 'for operating the contactarm 24 to effect engagement between the contact members 30 and 31. Uponengagement of the contact members 30 and 31, the switch 15 is operatedto' so energize the armature 11 as to effect rotation of the motor 10 ina counter-clock: wise direction, consequently, the electrode 4 is raisedto reduce the current flow through it.

In case the main magnet 20 were controlled solely by the current flowingthrough the electrode 4, the magnet 20 would not be operated to separatethe contactmembers 30 and 31 and prevent further operation of the motor10 until a normal amount of current was flowing through the electrode 4.Consequently, the motor 10 and themoving parts of the regulator wouldovertravel to raise the electrode 4 above the desired pointand,'accordingly, produce the so-called hunting action.

In order to prevent overtravel of the various moving parts of the systemand the resulting hunting action, the interlock switch member 38 isoperated simultaneously with the motor 10 to connect the winding 23across the are produced by the electrode 4. The winding 23 opposes theaction of the winding21 and, consequently, changes the setting of themagnet 20 to effect separation of the contact members 30 and 31 justprior to the obtaining of normal current conditions in the electrodecircuit.

If the current flow through the electrode 4 falls below normal value,the energization ofthe magnet 20 is reduced to effect engagement betweenthe contact members 30 and 32. Upon engagement between the contactmembers 30 and 32, the winding 40 is connected across the supplyconductors 13 and 14 for operating the switch 16 toefi'ect rotation ofthe motor 10 in 'a clockwise direction. The clockwise rotation of themotor 10 lowers the electrode 4 in the furnace to increase the currentflow through the electrode circuit. The interlock switch member 44 isoperated simultaneouslv with the motor 10 for connecting the winding 22across the arc produced by the electrode 4. The winding 22 assists thecurrent winding 21 and, consequently, increases the energization of themagnet 20 for so changing its setting as to effect disengagement of thecontact members 30 and 32 just prior to theobtaining of normal currentconditions in the electrode circuit and, accordingly, preventing huntingaction.

In a copending application, Serial No. 287,612, filed April 4, 1919, Ihave illustrated, described and claimed another furmace-regulator systemdisclosing other means for preventing hunting action in said system.

Modifications in the system and arrangement and location of parts may bemade within the spirit and scope of my invention, and such modificationsareintended to be covered by the appended claims.

I claim as my invention:

1. In a furnace-regulator system, the combination with a movableelectrode, of means comprising a main magnet having three windings foroperating said electrode, one of said windings being energized inaccordance with the electrode-circuit conditions and two of saidwindings being differentially-wound and selectively energized to preventhunting action.

2. In a furnace-regulator system, the combination with a movableelectrode, a motor for raising and lowering said electrode, and twoswitches for operating said motor in a forward and in a reversedirection, of a main magnet having a current winding for selectivelyoperating said switches to maintain a constant electrode arc, saidmagnet also having two differential windings selectively operated bysaid switches to prevent hunting action.

3. In a furnace-regulator system, the combination comprising a movableelectrode, a motor for raising and lowering said electrode, meanscomprising a main magnet for operating said motor to maintain a constantelectrode arc, and means comprising two diflerential windings forchanging the setting of said magnet .to prevent hunting.

action.

4. In a furnace-regulator system, in combination, a movable electrode,means comprising a main magnet for operating said electrode inaccordance with the value of the current flowing through it, twodifferential windings connected to the electrode circuit and operatingon said magnet, and means for selectively energizing said differentialwindings to prevent hunting action.

5. In a furnace-regulator system, the combination comprising a movableelectrode, means for raising and lowering said electrode, and controlmeans comprising a main magnet for governing the operation of saidfirst-mentioned means, said magnet having a winding energized inaccordance with the value of the current flowing through the electrodeand two differential windings selectively connected across the electrodearc to prevent hunting action.

6. In a regulator system, the combination comprising a movable member, asupply circuit connect'ed'to said member, means for operating saidmember and comprising an electromagnet having a winding energized inaccordance with the .Value of the current flowing through the supplycircuit and two difierential windings selectively connected value of thecurrent flowing through it,

and two differential windings co-operating with said magnet to preventhunting action.

8. In a furnace-regulator system, the combination comprising a movableelectrode, means for operating said electrode in accordance with thevalue of the current flowing through it, and means comprising twowindings selectively connected to the electrode circuit for preventinghunting action.

9. In a furnace-regulator system, the combination with a movableelectrode, a motor for raising and lowering said electrode, and twoswitches for operating said motor in a forward and in a reversedirection, of a main magnet having a winding energized in accordancewith the value of the current flowing through the electrode circuit forselectively operating said switches, said magnet also having twodifferential windings selectively connected to the electrode circuit bysaid switches for changing the setting of the magnet to prevent huntingaction.

10. In a furnace-regulator s stem, the

combination comprising amovab e electrode, a motor for raising andlowering said electrode, and means comprising a main magnet foroperating said motor to maintain a con stant electrode arc, said magnethaving three windings, one of said windings being energized inaccordance with the value of the current flowing through the electrodeand two of said windings being differentially wound and selectivelyconnectedacross the electrode arc to prevent hunting action.

11. In a furnace-regulator system, the combination comprising a movableelectrode, and means comprising a magnet having three windings forgoverning the operation of the electrode, one of said windings beingenergized in accordance with the value of the current flowing throughthe electrode and two of said windings being selectively connectedacross the electrode arc for cooperating with the first winding toprevent vember, 1919.

CLARENCE A. BODDIE.

